Wafer polishing apparatus, wafer polishing system and wafer polishing method

ABSTRACT

It is possible to execute a one-step polishing or a plural-step polishing at a high throughput, and it is possible to achieve a reduction of an occupied area on the basis of a compact structure of a whole apparatus. Two platens are respectively provided with a first wafer retention head and a second wafer retention head, and a wafer transfer apparatus on which a wafer is mounted is arranged between two platens. The two wafer retention heads are moved between two platens and the wafer transfer apparatus respectively by a first moving means and a second moving means. Further, a two-step polishing is executed by whirl moving two wafer retention heads from one platen to the other platen at 180 degree respectively by a whirl moving means supporting two moving means.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wafer polishing apparatus, a waferpolishing system and a wafer polishing method, and more particularly toa wafer polishing apparatus, a wafer polishing system and a waferpolishing method executing a polishing work according to one step or twoor more steps by using a plurality of platens.

2. Description of the Related Art

Conventionally, this kind of wafer polishing apparatus (CMP apparatus) 1is provided with a rotationally drivable platen 2, a polishing pad 3stuck to an upper surface of the platen 2, an upward and downwardmovable wafer retaining head 4 retaining a wafer, and a feed nozzle (notshown) feeding an abrasive agent to an upper surface of the polishingpad 3, as shown in FIG. 9, and the platen 2 is structured such as to berotated via a rotating shaft 6 on the basis of a drive of a motor 5.

At a time of polishing the wafer, the wafer is polished by pressing thewafer to the upper surface of the polishing pad 3 at a predeterminedpressure, and feeding the abrasive agent to the upper surface of thepolishing pad 3 while rotating the polishing pad 3 and the wafer.

In the case of CMP processing a plurality of wafers, in the view of animprovement of a throughput, there is a method of simultaneously CMPprocessing a plurality of wafers by arranging a plurality of wafers onthe same platen, however, since it is impossible to secure a uniformhigh work quality in all a plurality of wafers, there is employed amethod of CMP processing one wafer by one platen.

Further, in the case of mounting the wafers one by one on one platen andpolishing the wafer according to a one-step polishing, that is, in onestep, or polishing according to a two-step polishing, that is, in twosteps while changing a polishing condition (kind of the abrasive agent,a polishing pressure, a polishing speed and the like) in the middle, awaiting time is generated at a time of feeding the wafer to one platenor discharging the wafer from one platen. Accordingly, a throughput islowered.

In order to improve the throughput, there have been conventionallyproposed various polishing methods. For example, there is a structureobtained by combining one platen, and n sets of units (including acommon transfer apparatus) provided with a positioning means retainingone wafer retention head so as to be capable of positioning to onetransfer apparatus (for example, refer to patent documents 1 and 2).Further, there is a structure provided with n platens, and a positioningmeans retaining (n+1) wafer retention heads so as to be capable ofpositioning to one transfer apparatus (for example, refer to patentdocuments 3 and 4).

Further, there is a structure obtained by combing two platens, and twounits provided with a positioning means retaining a wafer retention headso as to be capable of positioning to one transfer apparatus, and usingone platen in common (for example, refer to patent documents 5 and 6).Further, there is a structure provided with two platens, and twopositioning means retaining a wafer retention head so as to be capableof positioning to a transfer apparatus, and making the positioning meansindependently controllable with each other (for example, refer to patentdocument 7).

Patent Document 1: Japanese Unexamined Patent Publication No. 11-204468

Patent Document 2: Japanese Unexamined Patent Publication No. 10-202515

Patent Document 3: Japanese Unexamined Patent Publication No. 09-174420

Patent Document 4: Japanese Unexamined Patent Publication No.2005-131772

Patent Document 5: Japanese Unexamined Patent Publication No.2003-332282

Patent Document 6: Japanese Unexamined Patent Publication No.2000-263433

Patent Document 7: Japanese Unexamined Patent Publication No.2000-117628

SUMMARY OF THE INVENTION

In the prior art described in the patent document 1 or 2, since it isdifficult to carry out a continuous polishing work in the case ofexecuting the two-step polishing, a processing efficiency is lowered.

Further, in the prior art described in the patent document 3 or 4, theCMP process can be carried out continuously without rehandling the waferin the case of executing the two-step polishing, however, the CMPprocess is carried out between a plurality of platens in the case ofexecuting the one-step polishing. Accordingly, a productivity is loweredat a time for moving the wafer between a plurality of platens.

Further, in the prior art described in the patent document 5 or 6, sincethere exists the platen which is not used, in the case of executing theone-step polishing, a size of the apparatus becomes large. Further, inthe prior art described in the patent document 7, the efficientpolishing work can be achieved in both of the one-step polishing and thetwo-step polishing, however, it is necessary to arrange the platen andthe transfer apparatus on a circumference, and a size of the apparatusbecomes large for securing a rigidity of the positioning means.

In the prior art, there has been generally employed a method ofsequentially executing a plural-step polishing on each of the platens byusing different kinds of abrasive agents and providing a plurality ofplatens per kinds of the abrasive agents, or a method of providing awafer retention head per a plurality of platens, however, each of themhas an advantage and a disadvantage. It is difficult to achieve a highthroughput in both of the one-step polishing and the plural-steppolishing, the numbers of the platens and the wafer retention heads areincreased, and there is a problem that a whole size of the apparatus isenlarged.

Accordingly, in the case of carrying out the one-step polishing by usingone platen, or in the case of carrying out the plural-step polishing bysequentially using a plurality of platens, there is generated atechnical problem to be solved for polishing the wafer at a highthroughput and reducing an occupied space without enlarging a whole ofthe apparatus. An object of the present invention is to solve theproblem.

The present invention is proposed for achieving the object mentionedabove. According to the invention described in claim 1, there isprovided a wafer polishing apparatus polishing a wafer by pressing thewafer retained by a wafer retention head to a polishing pad on a platen,comprising: a first platen and a second platen provided in parallelwhile having a gap from each other; a first wafer retention head and asecond wafer retention head respectively installed above the firstplaten and the second platen and being movable up and down; a wafertransfer apparatus arranged between the first platen and the secondplaten and on which the wafer before being polished and the wafer afterbeing polished are mounted; a first moving means moving and stopping thefirst wafer retention head to both positioning portions of the firstplaten and the wafer transfer apparatus; a second moving means movingand stopping the second wafer retention head to both positioningportions of the second platen and the wafer transfer apparatus; and athird moving means supporting the first moving means and the secondmoving means, and whirling around the wafer transfer apparatus so as tomove and stop the first wafer retention head and the second waferretention head respectively to the positioning portions of the secondplaten and the first platen, wherein the wafer polished by the firstplaten or the second platen is whirled and moved to the positioningportion of the second platen or the first platen so as to be polished.

According to this structure, in the case of the one-step polishing, thefirst platen and the second platen polish by setting their polishingconditions identical. First, the first wafer retention head is moved tothe positioning portion of the wafer transfer apparatus by the firstmoving means so as to retain the wafer, and the polishing work isstarted by moving the wafer retention head to the positioning portion ofthe first platen. In slightly retard of this, after the second wafer ismounted to the wafer transfer apparatus, the wafer is retained by thesecond wafer retention head in the same manner as mentioned above, andis moved to the positioning portion of the second platen, and thepolishing work is started.

As mentioned above, two wafers are sequentially and independently movedto the first platen and the second platen respectively so as to bepolished, the polished wafers are sequentially moved to the wafercarry-out portion on the wafer transfer apparatus so as to bedischarged, thereafter the third wafer and the fourth wafer carried inthe wafer transfer apparatus are retained by the first wafer retentionhead and the second wafer retention head respectively, and the one-steppolishing is repeated in the same procedure as mentioned above.

Further, in the case of the two-step polishing, the first platen and thesecond platen polish by differentiating the polishing conditions. First,the first wafer is mounted to a wafer carry-in position of the wafertransfer apparatus, the first wafer retention head is thereafter movedto the wafer carry-in position of the wafer transfer apparatus by thefirst moving means so as to retain the wafer, and the first waferretention head is next moved to the polishing position of the firstplaten so as to start polishing.

On the other hand, the second wafer retention head is moved to the waferfeed portion on the wafer transfer apparatus by the second moving meansso as to retain the second wafer. Further, after the end of thepolishing of the first wafer, the first wafer retention head is whirledand moved to the polishing position of the second platen by the thirdmoving means, and the second wafer is moved to the polishing position ofthe first platen by the second moving means so as to start polishing.

After the end of the polishing of the first wafer, the first waferretention head is moved to the wafer transfer apparatus so as todischarge the first wafer, and thereafter retains the third waferinstead. Further, after the end of the polishing of the second wafer,the second wafer retention head is whirled and moved to the polishingposition of the second platen by the third moving means so as to startpolishing. Thereafter, the two-step polishing is sequentially carriedout by the first platen and the second platen, by repeating the stepsmentioned above.

According to the invention described in claim 2, there is provided awafer polishing apparatus polishing a wafer by pressing the waferretained by a wafer retention head to a polishing pad on a platen,comprising: a first platen and a second platen provided in parallelwhile having a gap from each other; a first wafer retention head and asecond wafer retention head respectively installed above the firstplaten and the second platen and being movable up and down; a wafertransfer apparatus arranged between the first platen and the secondplaten and on which the wafer before being polished and the wafer afterbeing polished are mounted; a first moving means moving and stopping thefirst wafer retention head to both positioning portions of the firstplaten and the wafer transfer apparatus; a second moving means movingand stopping the second wafer retention head to both positioningportions of the second platen and the wafer transfer apparatus; and athird moving means supporting the first moving means and the secondmoving means, and whirling around the wafer transfer apparatus so as tomove and stop the first wafer retention head and the second waferretention head respectively to the positioning portions of the secondplaten and the first platen, wherein the wafer polished by the firstplaten or the second platen is whirled and moved to the positioningportion of the second platen or the first platen so as to be polished, apartition wall for preventing a liquid from flying in all directions isprovided between the first platen and the wafer transfer apparatus, andbetween the second platen and the wafer transfer apparatus, a passagethrough which the first wafer retention head and the second waferretention head pass is formed in the partition wall, and the partitionwall is provided in such a manner as to be capable of integrallywhirling with the third moving means.

According to this structure, the same operation as claim 1 can beachieved. In addition, even if the first platen and the second platenare arranged close to each other, it is possible to prevent the abrasiveagent or the like fed to one of two platens from flying in alldirections toward the other platen during the polishing work because thepartition wall is provided between each of the platens and the wafertransfer apparatus. Further, since the passage allowing the movement ofeach of the wafer retention heads is formed in the partition wall, andthe partition wall is attached so as to be capable of integrallywhirling with the third moving means, the wafer retention head is movedbetween two platens and the wafer transfer apparatus without beinginterfered with the partition wall.

According to the invention described in claim 3, there is provided awafer polishing apparatus as described in claim 1 or 2, wherein thewafer transfer apparatus is provided with a wafer carry-in meanscarrying in the unpolished wafer, and a wafer carry-out means carryingout the polished wafer, and the wafer carry-out means and the wafercarry-in means are structured such as to be independently movable to aposition corresponding to a center position of whirling of the thirdmoving means.

According to this structure, the wafer carry-in means and the wafercarry-out means are moved to the position corresponding to the centerposition of whirling of the third moving means independently from eachother in alternate shifts. Accordingly, the unpolished wafer is retainedby the wafer retention head after being set to the wafer feed portion onthe wafer transfer apparatus by the wafer carry-in means. Further, thepolished wafer is carried out to the outer portion by the wafercarry-out means after being set to the wafer discharge portion on thewafer transfer apparatus by the wafer retention head.

According to the invention described in claim 4, there is provided awafer polishing apparatus as described in claim 1, 2 or 3, wherein thethird moving means is provided so as to be retractable from the centerposition of whirling, and ahead cleaning apparatus for cleaning thefirst wafer retention head and the second wafer retention head isinstalled at the center position of whirling.

According to this structure, the first wafer retention head or thesecond wafer retention head is cleaned by the head cleaning apparatus byretracting the third moving means to a predetermined position from thecenter position of whirling at a time of cleaning the first waferretention head or the second wafer retention head.

According to the invention described in claim 5, there is provided awafer polishing system provided with the wafer polishing apparatus asdescribed in claim 1 or 2, wherein two or more the wafer polishingapparatuses are provided in parallel, and a transfer apparatus fortransferring the wafer polished by one wafer polishing apparatus to theother wafer polishing apparatus installed in adjacent thereto isprovided between the adjacent wafer polishing apparatuses.

According to this structure, three or more steps of polishing can beachieved by polishing the wafer by the one wafer polishing apparatus andthereafter transferring the wafer to the adjacent wafer polishingapparatus by the transfer apparatus so as to further polish. Forexample, in the case of polishing the wafer in the wafer polishingsystem in which two wafer polishing apparatuses are provided inparallel, the wafer is CMP processed according to the two-step polishingby one of two wafer polishing apparatuses, and the wafer can bethereafter transferred to the other wafer polishing apparatus so as tobe further CMP processed according to the one-step polishing or thetwo-step polishing. Accordingly, the three-step polishing or thefour-step polishing is executed as whole with respect to the wafer.

According to the invention described in claim 6, there is provided awafer polishing method of polishing a wafer by the wafer polishingsystem as described in claim 5 in which two wafer polishing apparatusesare provided in parallel, comprising: a step of transferring the waferto one of two wafer polishing apparatuses so as to execute a one-steppolishing or a two-step polishing; a step of transferring the waferexecuted the one-step polishing or the two-step polishing to the otherwafer polishing apparatus by a transfer apparatus; and a step of furtherapplying the one-step polishing or the two-step polishing to the waferby the other wafer polishing apparatus, wherein a three-step polishingor a four-step polishing is applied as a whole to the wafer.

According to this method, after the wafer is first transferred to theone wafer polishing apparatus so as to be applied the one-step polishingor the two-step polishing, the wafer is transferred to the other waferpolishing apparatus by the transfer apparatus. Further, the one-steppolishing or the two-step polishing is further applied to the wafer.Accordingly, the three-step polishing or the four-step polishing isapplied to the wafer as a whole.

In the invention described in claim 1, since the polishing work iscontinuously carried out without generating a waiting time in both ofthe case of alternately carrying out the one-step polishing at twoportions by using one platen, and the case of carrying out the two-steppolishing by sequentially using two platens, it is possible to obtain ahigh throughput. Further, since two platens provided in close parallelin both of the one-step polishing and the two-step polishing is used, itis possible to achieve a compact structure having a small occupied spacein addition that a productivity is improved.

Further, since the continuous polishing work is not affected by a rateof a process time for each of the polishing works in any of the one-steppolishing case and the two-step polishing case, it is possible to carryout the one-step polishing or the two-step polishing having a goodproductivity. Particularly, after the first polishing step and thesecond polishing step are finished in the two-step polishing, it ispossible to smoothly give way to the next polishing motion immediately,one of the first polishing step and the second polishing step is notstood to the other polishing work condition, and it is possible to wellprevent a corrosion of the wafer worked surface by the waiting time.

In the invention described in claim 2, since it is possible to inhibitthe abrasive agent from flying in all directions from one of two platensto the other by the partition wall, it is possible to prevent anenvironment pollution due to the abrasive agent flying in alldirections, in addition to the effect of the invention described inclaim 1. Further, there is no risk that the different kinds of abrasiveagents are mixed with each other, and a working quality of the wafer isimproved. Further, the wafer retention head can smoothly move betweenthe platen and the wafer transfer apparatus without interfering with thepartition wall.

In the invention described in claim 3, since the wafer carry-in meansand the wafer carry-out means can move to the position corresponding tothe center position of whirling of the third moving means, it ispossible to accurately mount the unpolished wafer to the wafer feedposition on the wafer transfer apparatus by the wafer carry-in means, inaddition to the effect of the invention described in claim 1 or 2.Further, it is possible to securely carry out the polished wafer mountedto the wafer discharge position on the wafer transfer apparatus by thewafer carry-out means. Since the wafer transfer apparatus exists in thecenter of whirling of the third moving means, it is possible to freelyposition the other wafer retention head to two platens by using thethird moving means even at a time when the first wafer retention head orthe second wafer retention head feeds or discharges the wafer withrespect to the wafer transfer apparatus.

In the invention described in claim 4, since the head cleaning apparatusis installed at the center position of whirling of the third movingmeans, it is possible to easily and rapidly clean the wafer retentionhead only by moving the wafer retention head to the center position ofwhirling while being compact in the structure, in addition to the effectof the invention described in claim 1, 2 or 3. Since the head cleaningapparatus exists in the center of whirling of the third moving means, itis possible to freely position the other wafer retention head to twoplatens by using the third moving means even at a time when the firstwafer retention head or the second wafer retention head carries out thehead cleaning by the head cleaning apparatus.

In the invention described in claim 5, since it is possible to carry outa plurality of (three or more) desired steps of polishing bysequentially transferring the wafer to two or more wafer polishingapparatuses so as to carry out the polishing work, it is possible toeasily obtain the wafer having a high working quality.

In the invention described in claim 6, since it is possible to carry outthe three-step polishing or the four-step polishing by sequentiallytransferring the wafer to two wafer polishing apparatuses so as to carryout the polishing work in a plurality of steps, it is possible to easilymanufacture the wafer having a higher polishing quality than theconventional one while maintaining an improvement of the productivity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an embodiment according to the presentinvention and showing a wafer polishing system;

FIG. 2 is a plan view showing an example of a layout of a platen, awafer transfer apparatus and the like in a wafer polishing portionaccording to the embodiment;

FIG. 3 is a side elevational view showing a whirl moving means and aportion near a partition wall according to the embodiment partly using across section;

FIG. 4 is a plan view showing an installed example of an upper wallportion of the partition wall according to the embodiment;

FIG. 5 is a plan view showing an installed example of a lower wallportion of the partition wall according to the embodiment;

FIGS. 6A to 6E show a main portion of a wafer polishing apparatusaccording to the embodiment, and are step diagrams explaining respectivemotions of a one-step polishing;

FIGS. 7A to 7J show a main portion of the wafer polishing apparatusaccording to the embodiment, and are step views explaining respectivemotions of a two-step polishing;

FIG. 8 is a plan view of a wafer polishing system exemplifying the otherembodiment according to the present invention; and

FIG. 9 is a perspective view of the wafer polishing apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is provided for achieving the object that it ispossible to polish the wafer at a high throughput and it is possible toreduce the occupied space without enlarging a whole of the apparatus, inthe case of carrying out the one-step polishing by using one platen, orin the case of carrying out the plural-step polishing by sequentiallyusing a plurality of platens. The present invention achieves the objectmentioned above by a wafer polishing apparatus polishing a wafer bypressing the wafer retained by a wafer retention head to a polishing padon the platen, comprising: a first platen and a second platen providedin parallel while having a gap from each other; a first wafer retentionhead and a second wafer retention head respectively installed above thefirst platen and the second platen and being movable up and down; awafer transfer apparatus arranged between the first platen and thesecond platen and on which the wafer before being polished and the waferafter being polished are mounted; a first moving means moving andstopping the first wafer retention head to both positioning portions ofthe first platen and the wafer transfer apparatus; a second moving meansmoving and stopping the second wafer retention head to both positioningportions of the second platen and the wafer transfer apparatus; and athird moving means supporting the first moving means and the secondmoving means, and whirling around the wafer transfer apparatus so as tomove and stop the first wafer retention head and the second waferretention head respectively to the positioning portions of the secondplaten and the first platen, wherein the wafer polished by the firstplaten or the second platen is whirled and moved to the positioningportion of the second platen or the first platen so as to be polished.

Embodiment

A description will be given below of an embodiment according to thepresent invention with reference to FIGS. 1 to 8. The present embodimentcan achieve a one-step polishing at a high throughput by being provideda first wafer retention head and a second wafer retention headrespectively installed above a first platen and a second platen,arranging a wafer transfer apparatus mounting a wafer thereon betweentwo platens, and respectively moving the first wafer retention head andthe second wafer retention head to both positioning portions of twoplatens and the wafer transfer apparatus by a first moving means and asecond moving means.

Further, it is possible to achieve a two-step polishing at a highthroughput by respectively whirl moving two wafer retention heads to theplaten in the opposite side by a whirl moving means (a third movingmeans) supporting two moving means. Further, since two platens and themoving means can be arranged compact, it is possible to achieve areduction of an occupied area without enlarging a size of a whole of theapparatus.

FIG. 1 is a plan view showing a whole structure of a CMP system 11according to the present embodiment. As shown in FIG. 1, the CMP system11 is provided with a wafer polishing portion 12, a wafer cleaningportion 13 provided in one side of the wafer polishing portion 12, and awafer storage portion 14 provided in one side of the wafer cleaningportion 13, and a cleaning apparatus 15 and a wafer storing cassette 16are respectively installed in the wafer cleaning portion 13 and thewafer storing portion 14.

The wafer carried in the wafer polishing portion 12 is CMP processedaccording to a one-step polishing or a two-step polishing, the polishedwafer is transferred to a carrier robot 17 so as to be fed to the wafercleaning portion 13, and is cleaned by the cleaning apparatus 15.Further, the cleaned wafer is transferred to a carrier robot 18 so as tobe fed to the wafer storage portion 14, and is stored in the waferstoring cassette 16.

Next, a description will be given in detail of a structure of the CMPapparatus 10 installed to the wafer polishing portion 12. A first platen21 and a second platen 22 which can be rotationally driven by a motor(not shown) are provided in the wafer polishing portion 12 in parallelso as to have a predetermined interval, and a first polishing pad 24 anda second polishing pad 25 are respectively stuck to upper surfaces ofthe first platen 21 and the second platen 22. Further, a wafer transferapparatus 23 is arranged between the first platen 21 and the secondplaten 22, and the unpolished wafer and the polished wafer are mountedto the wafer transfer apparatus 23.

Further, above the first polishing pad 24 and the second polishing pad25, there are provided a first wafer retention head 26 and a secondwafer retention head 27 which respectively press the wafer to thepolishing pads 24 and 25 at predetermined pressures while retaining thewafer and can move up and down and can be rotationally driven, and feednozzles (not shown) which respectively feed an abrasive agent onto thepolishing pads 24 and 25.

Accordingly, a lower surface of the wafer is polished by pressing thewafer retained by each of the wafer retention heads 26 and 27 to anupper surface of each of the polishing pads 24 and 25 and feeding theabrasive agent onto the polishing pads 24 and 25 while rotating thepolishing pads 24 and 25 and the wafer.

The wafer transfer apparatus 23 is provided with a wafer feed means 28and a wafer discharge means 29, as shown in FIG. 2, and the wafer feedmeans 28 can be moved to a wafer carry-in position 31, and receives theunpolished wafer from the carrier robot at the wafer carry-in position31 so as to feed to the wafer retention head 26 and 27. Further, thewafer discharge means 29 can be moved to a wafer carry-out position 32,and transfers the processed wafer received from the wafer retentionheads 26 and 27 to the carrier robot 17.

Further, a first moving means 33 and a second moving means 34 areprovided above the wafer transfer apparatus 23 and the platens 21 and22. As a drive system of the first moving means 33 and the second movingmeans 34, it is possible to employ a ball screw drive system, an aircylinder drive system or the like. Further, the first wafer retentionhead 26 and the second wafer retention head 27 are movably supportedrespectively by the first moving means 33 and the second moving means34.

Accordingly, the first wafer retention head 26 is reciprocated betweenthe wafer transfer apparatus 23 and the first platen 21 by the firstmoving means 33, whereby the first wafer retention head 26 is moved tothe wafer transfer apparatus 23 and the polishing positions of the firstplaten 21 so as to be positioned. In other words, the first waferretention head 26 is structured such as to be moved to and stopped atthe positioning portions (the polishing position and the wafer transferposition) of both the first platen 21 and the wafer transfer apparatus23 by the first moving means 33.

In the same manner, the wafer retention head 27 is reciprocated betweenthe wafer transfer apparatus 23 and the second platen 22 by the secondmoving means 34, whereby the second wafer retention head 27 is moved tothe wafer transfer apparatus 23 and the polishing position of the secondplaten 22 so as to be positioned. In other words, the second waferretention head 27 is structured such as to be moved to and stopped atthe positioning portions (the polishing position and the wafer transferposition) of both the second platen 22 and the wafer transfer apparatus23 by the second moving means 34.

Further, a whirl moving means 35 corresponding to the third moving meansis additionally provided above the wafer transfer apparatus 23. Thewhirl moving means 35 supports the first moving means 33 and the secondmoving means 34, whirls around the wafer transfer apparatus 23, andrespectively moves and stops the first wafer retention head 26 and thesecond wafer retention head 27 to the positioning portions (thepolishing positions) of the second plate 22 and the first platen 21.

Accordingly, the first wafer retention head 26 is horizontally whirledat 180 degree around the wafer transfer apparatus 23 together with thefirst moving means 33 by the whirl moving means 35, thereby beingrotationally moved to the polishing position of the second platen 22 inan opposite side to the first platen 21 so as to be stopped. In the samemanner, the second wafer retention head 27 is horizontally whirled at180 degree around the wafer transfer apparatus 23 together with thesecond moving means 34 by the whirl moving means 35, thereby beingrotationally moved to the polishing position of the first platen 21 inan opposite side to the second platen 22 so as to be stopped. In thiscase, the wafer carry-out means 31 and the wafer carry-in means 32mentioned above are structured at a position corresponding to the centerposition of whirling of the whirl moving means 35 such as to bealternately movable independently from each other.

The whirl moving means 35 has a whirl support portion (not shown) in anouter peripheral portion of a member to which the first moving means 33and the second moving means 34 are supported, as shown in FIG. 3, and isrotationally driven by a motor (not shown). The first wafer retentionhead 26 and the second wafer retention head 27 are arranged in an outerperipheral portion of the whirl moving means 35 so as to face to eachother.

Accordingly, the whirl moving means 35 is reciprocated at 180 degreeaccording to a motor drive, whereby the first wafer retention head 26and the second wafer retention head 27 are whirl moved between the firstplaten 21 and the second platen 22.

In the present embodiment, a partition wall 38 for preventing a liquidfrom flying in all directions is provided between the first platen 21and the wafer transfer apparatus 23, and between the second platen 22and the wafer transfer apparatus 23, in order to prevent the liquid suchas the abrasive agent or the like fed to the upper surface of the firstplaten 21 or the second platen 22 under rotation from flying in alldirections toward the second platen 22 or the first platen 21 arrangedso as to oppose to the first platen 21 and the second platen 22.

As shown in FIG. 3, the partition wall 38 is constituted by an upperwall portion 39 and a lower wall portion (an auxiliary wall portion) 40.The upper wall portion 39 is attached in such a manner as to be whirledintegrally with the whirl moving means 35, and the upper wall portion 39in a plan view is constituted by a pair of vertical surface portions 41arranged between the first platen 21 and the second platen 22, andcircular arc surface portions 42 and 43 formed so as to correspond tothe outer peripheral shapes of the first platen 21 and the second platen22 from both ends of the vertical surface portion 41, as shown in FIG.4.

Further, a passage 44 communicating between the first platen 21 and thesecond platen 22 is formed in an inner side of a pair of verticalsurface portions 41, and the passage 44 allows the first wafer retentionhead 26 and the second wafer retention head 27 to move. Accordingly, thefirst wafer retention head 26 and the second wafer retention head 27 areformed by the passage 44 in such a manner as to be movable withoutinterfering with the partition wall 38.

The lower wall portion 40 is constituted by a circular arc surfaceportion 45 fixed between the wafer transfer apparatus 23, and the firstplaten 21 and the second platen 22, and a horizontal surface portion 46continuously provided in such a manner as to cover the upper surfaces ofthe first platen 21 and the second platen 22 from an upper end of thecircular arc surface portion 45 (refer to FIG. 5).

Since the partition wall 38 is installed between the platens 21 and 22,and the wafer transfer apparatus 23, the abrasive agent fed to the uppersurface of the first platen 21 or the second platen 22 during the waferpolishing is prevented from flying in all directions toward the uppersurface of the second platen 22 or the first platen 21 in the oppositeside. Since a prior art (not shown) is provided for cleaning theabrasive agent flying in all directions toward the wall by a pure wateror the like, and the abrasive agent flying in all directions toward thewall can be cleaned before the upper wall portion 39 is moved by thewhirl moving means 35, the abrasive agents respectively used in thefirst platen 21 and the second platen 22 are not brought in the secondplaten 22 and the first platen 21 even if the upper wall portion 39 iswhirled.

Next, a description will be given of an operation of the presentembodiment. Each of motion portions constructing the CMP system 11 isgenerally controlled according to a predetermined motion program by acontrol apparatus (not shown). FIGS. 6A to 6E show motion steps at atime of CMP processing the wafer according to the one-step polishing. Inthis case, as a matter of convenience for explaining, an illustration ofthe moving means 33, 34, and 35 is omitted in these drawings.

In this case, polishing conditions such as the abrasive agent and thelike respectively set in the first platen 21 and the second platen 22for applying the one-step polishing to the wafer in the first platen 21and the second platen 22 are identical with each other.

First, after mounting the wafer to the wafer feed portion 28 of thewafer transfer apparatus 23 shown in FIG. 3, the first wafer retentionhead 26 is moved to the receiving position of the wafer transferapparatus 23 by the first moving means 33 (FIG. 6A). Next, the firstwafer retention head 26 receives the wafer on the wafer transferapparatus 23 (FIG. 6B), the first wafer retention head 26 is moved tothe polishing position on the first platen 21 by the first moving means33 so as to start the polishing work (FIG. 6C).

During the polishing, the wafer to be polished next is mounted on thewafer transfer apparatus 23, and the second wafer retention head 27 isthereafter moved to the receiving position of the wafer transferapparatus 23 by the second moving means 34, and receives the wafer (FIG.6D). Further, the second wafer retention head 27 is moved to thepolishing position on the second platen 22 by the second moving means 34so as to start the polishing work (FIG. 6E).

Accordingly, the first wafer retention head 26 polishes the wafer on thefirst platen 21, and the second wafer retention head 27 simultaneouslypolishes the wafer on the second platen 22.

Next, if the polishing of the wafer on the first platen 21 is finished,the first wafer retention head 26 is moved to the positioning portion ofthe wafer transfer apparatus 23 by the first moving means 33 (FIG. 6A).Then, the first wafer retention head 26 discharges the polished wafer,and receives the unpolished wafer fed onto the wafer transfer apparatus23 instead (FIG. 6B). Thereafter, the first wafer retention head 26 ismoved to the polishing position on the first platen 21 by the firstmoving means 33 so as to start the polishing work (FIG. 6C).

On the other hand, if the polishing of the wafer on the second platen 22is finished, the second wafer retention head 27 is moved to thepositioning portion of the wafer transfer apparatus 23 by the secondmoving means 34. Further, the second wafer retention head 27 dischargesthe polished wafer, and receives the unpolished wafer fed onto the wafertransfer apparatus 23 instead (FIG. 6D).

Thereafter, the second wafer retention head 27 is moved to the polishingposition on the second platen 22 by the second moving means 34 so as tostart the polishing work. Accordingly, the first wafer retention head 26again polishes the wafer on the first platen 21, and the second waferretention head 27 simultaneously polishes the wafer on the second platen22 (FIG. 6E). Thereafter, the one-step polishing is efficiently executedin each of the first platen 21 and the second platen 22 by sequentiallyrepeating the series of motion steps shown in FIGS. 6A to 6E.

In other words, the first wafer retention head 26 is moved to thepolishing position on the first platen 21 so as to start the polishingwork after moving to the receiving position of the wafer transferapparatus 23 so as to receive the unpolished wafer. During the while,the wafer to be polished next is mounted on the wafer transfer apparatus23, and the second wafer retention head 27 is moved to the receivingposition of the wafer transfer apparatus 23 so as to receive the wafer,and is thereafter moved to the polishing position on the second platen22 so as to start the polishing work.

Accordingly, the first wafer retention head 26 executes the polishingwork on the first platen 21, and the second wafer retention head 27simultaneously executes the polishing work on the second platen 22. Alot of wafers can be efficiently polished by sequentially repeating theseries of polishing motions.

As mentioned above, it is possible to apply the one-step polishing tothe wafer in the first platen 21 and the second platen 22 in thesimultaneous parallel manner. In this case, since any waiting time isnot generated, a high throughput can be secured.

In the description of the one-step polishing mentioned above, the caseof the one kind of wafer process is exemplified, however, the motionsteps mentioned above can be applied to a case that two kinds ofone-step polishing are executed to two kinds of wafers in the firstplaten 21 and the second platen 22 in the simultaneous parallel mannerwhile changing the abrasive agent.

Next, FIGS. 7A to 7J show polishing motion steps in the case of CMPprocessing the wafer according to the two-step polishing. In this case,in order to apply the two-step polishing to the wafer by using both thefirst platen 21 and the second platen 22, the polishing conditions suchas the abrasive agent and the like in the first platen 21 and the secondplaten 22 are differentiated from each other. In the illustratedembodiment, after the polishing of the first step is executed on thefirst platen 21, the polishing of the second step is executed on thesecond platen 22.

First, after mounting the wafer to the wafer feed portion 28 of thewafer transfer apparatus 23 shown in FIG. 3, the first wafer retentionhead 26 is moved to the transfer position on the wafer transferapparatus 23 by the first moving means 33 (FIG. 7A). Next, the firstwafer retention head 26 receives the wafer on the wafer transferapparatus 23 (FIG. 7B), the first wafer retention head 26 is moved tothe polishing position on the first platen 21 by the first moving means33 so as to start the polishing work of the first step (FIG. 7C).

During the polishing, the wafer to be polished next is mounted to thewafer feed portion 28 of the wafer transfer apparatus 23, and the secondwafer retention head 27 is thereafter moved to the receiving position ofthe wafer transfer apparatus 23 by the second moving means 34. Further,the second wafer retention head 27 is moved onto the wafer transferapparatus 23 by the second moving means 34 so as to receive the wafer(FIG. 7D).

Next, if the polishing of the first step applied to the wafer isfinished on the first platen 21, the first wafer retention head 26 iswhirl moved to the polishing position on the second platen 22 by thewhirl moving means 35 so as to start applying the polishing work of thesecond step to the wafer (FIGS. 7E and 7F). Further, the second waferretention head 27 is moved to the polishing position on the first platen21 by the second moving means 34 so as to start the polishing work ofthe first step (FIG. 7G).

Accordingly, the first wafer retention head 26 executes the polishingwork of the second step on the second platen 22, and the second waferretention head 27 simultaneously executes the polishing work of thefirst step on the first platen 21.

Further, if the polishing work of the second step applied to the waferis finished on the second platen 21, the first wafer retention head 26is moved to the receiving position on the wafer transfer apparatus 23 bythe first moving means 33 (FIG. 7H), discharges the polished wafer, andreceives the unpolished wafer fed onto the wafer transfer apparatus 23instead.

On the other hand, if the polishing of the first step on the firstplaten 21 is finished, the second wafer retention head 26 is whirl movedto the polishing position on the second platen 22 by the whirl movingmeans 35 so as to start applying the polishing work of the second stepto the wafer (FIGS. 7I and 7J). Thereafter, the first wafer retentionhead 26 is moved to the polishing position on the first platen 21 by thefirst moving means 33 so as to again start the polishing work of thefirst step.

Thereafter, the two-step polishing applied to the wafer is efficientlyexecuted by sequentially repeating the series of motion steps shown inFIGS. 7A to 7J.

In the present embodiment, a head cleaning apparatus (refer to referencenumeral 48 in FIG. 1) for cleaning the wafer retention heads 26 and 27is installed in a center position of whirling of the whirl moving means35, and the wafer feed means 28 and the wafer discharge means 29 arestructured such as to be retracted from the center position of whirlingto the wafer carry-in position 32 and the wafer carry-out position 32respectively at a time of cleaning the wafer retention heads 26 and 27.

Accordingly, the cleaning process of the wafer retention heads 26 and 27is executed by retracting the wafer feed means 28 and the waferdischarge means 29 to the desired positions from the center position ofwhirling and thereafter moving the wafer retention heads 26 and 27 tothe head cleaning apparatus 48 installed at the center position ofwhirling, at a time of cleaning the wafer retention heads 26 and 27.

According to this structure, since the head cleaning apparatus 48 isinstalled at the center position of whirling of the whirl moving means35, it is possible to achieve a compact structure of the wholeapparatus, and it is possible to easily and rapidly clean the waferretention heads 26 and 27 by moving the wafer retention heads 26 and 27to the center position of whirling.

Further, since the wafer transfer apparatus 23 including the wafer feedmeans 28 and the wafer discharge means 29 and the head cleaningapparatus 48 exist at the center of whirling, the wafer retention head26 (27) is positioned at the center of whirling until the waferretention head 26 (27) mounts the processed wafer to the wafer dischargemeans 29, thereafter cleans by the head cleaning apparatus 48 andreceives the wafer to be processed from the wafer feed means 28, wherebythe other wafer retention head 27 (26) can be whirled between the firstplaten 21 and the second platen 22, and does not back up the polishingprocess.

As described above, since the present embodiment can independently andcontinuously execute the polishing work without generating any waitingtime in both of the case that the one-step polishing is carried out byusing one platen 21 or 22 and the case that the two-step polishing iscarried out by sequentially using two platens 21 and 22, it is possibleto obtain a high throughput.

Further, in both of the one-step polishing and the two-step polishing,it is possible to always operate two platens 21 and 22 which areprovided in close parallel so as to polish. Accordingly, a productivityof the polishing work is significantly improved, and it is possible toachieve a compact structure so as to reduce an occupied space of thewhole apparatus.

Further, in any case of the one-step polishing and the two-steppolishing, since it is possible to smoothly apply the continuouspolishing work to the wafer without being affected by the rate of theprocess time for each of the polishing works, it is possible to executethe one-step polishing or the two-step polishing having a goodproduction efficiency. Particularly, since it is possible to smoothlygive way to the next polishing work immediately after the firstpolishing step and the second polishing step are finished in thetwo-step polishing, one of the first polishing step and the secondpolishing step is neither stood to nor stopped its motion by the otherpolishing work condition.

In the illustrated embodiment, since the partition wall 38 is providedbetween each of the platens 21 and 22 and the wafer transfer apparatus23, there is no risk that the liquid such as the abrasive agent or thelike fed to one of two platens 21 and 22 flies in all directions towardthe other platen 21 or 22 during the polishing work, and it is possibleto always maintain the polishing environment clean.

Further, the passage 44 allowing each of the wafer retention heads 26and 27 to move is formed in the partition wall 38, and the partitionwall 38 is attached to the whirl moving means 35 so as to be integrallywhirled. Accordingly, the wafer retention heads 26 and 27 can besmoothly reciprocated to the predetermined positioning portion betweentwo platens 21 and 22 and the wafer transfer apparatus 23, without beinginterfered with the partition wall 38.

Further, the wafer feed means 28 and the wafer discharge means 29 can bemoved to the position corresponding to the center position of whirlingof the whirl moving means 35 independently from each other in alternateshifts. Accordingly, after the unpolished wafer is accurately set to thewafer feed means 28 from the carrier robot 17 at the wafer carry-inposition 31, the wafer feed means 28 is moved to the position of thewafer transfer apparatus 23, and the wafer is thereafter retainedefficiently by the wafer retention heads 26 and 27.

Further, after the polished wafer is set to the wafer discharge means 29on the wafer transfer apparatus 23 by the wafer retention heads 26 and27, the wafer discharge means 29 is moved to the wafer carry-outposition 31 and is transferred to the carrier robot 17 from the waferdischarge means 29.

FIG. 8 is a plan view showing the other embodiment according to thepresent invention. The wafer polishing portion 12 is provided with twoCMP apparatuses, that is, a first CMP apparatus 10A and a second CMPapparatus 10B having the same structure as the embodiment mentionedabove in parallel. In the illustrated embodiment, the first CMPapparatus 10A and the second CMP apparatus 10B are arranged so as toform a truncated chevron shape in a plan view, and the first platen 21of the first CMP apparatus 10A and the second platen 22 of the secondCMP apparatus 10B are arranged so as to come close to each other.

Further, a transfer apparatus 49 is installed between the first CMPapparatus 10A and the second CMP apparatus 10B. The transfer apparatus49 transfers the wafer polished by the first CMP apparatus 10A to thesecond CMP apparatus 10B.

As mentioned above, according to the wafer polishing system 11 in FIG.8, it is possible to execute the CMP process according to the one-steppolishing or the two-step polishing by CMP processing the waferaccording to the two-step polishing by one wafer polishing apparatus 10Aand thereafter transferring the wafer to the other wafer polishingapparatus 10B.

Accordingly, it is possible to apply the three-step polishing or thefour-step polishing to the wafer as a whole, and it is possible toeasily obtain the wafer having a high work quality. The high throughputcan be achieved by respectively carrying out the same one-step polishingand two-step polishing. Further, it is also possible to simultaneouslyprocess plural kinds of wafers by independently carrying out thedifferent one-step polishing and two-step polishing respectively.

The first moving means 33 and the second moving means 34 are shown onthe basis of the linear motion in the embodiment and the description ofthe motion according to the present invention, however, it is sufficientto position the wafer retention head to the platen 21 (22) and the wafertransfer apparatus 23 respectively, and it is possible to obtain theeffect even if the moving means carries out the whirling motion.

The present invention can be variously modified within the scope of thepresent invention, and it goes without saying that the present inventioncomes to the modified structure.

DESCRIPTION OF REFERENCE NUMERALS

-   10 wafer polishing apparatus (CMP apparatus)-   11 wafer polishing system (CMP system)-   12 wafer polishing portion-   21 first platen-   22 second platen-   23 wafer transfer apparatus-   24 first polishing pad-   25 second polishing pad-   26 first wafer retention head-   27 second wafer retention head-   28 wafer feed means-   29 wafer discharge means-   31 wafer carry-in position-   32 wafer carry-out position-   33 first moving means-   34 second moving means-   35 whirl moving means (third moving means)-   38 partition wall-   44 passage-   48 head cleaning apparatus-   49 transfer apparatus (distributing means)

1. A wafer polishing apparatus that polishes a wafer by pressing thewafer retained by a wafer retention head to a polishing pad on a platen,comprising: a first platen and a second platen provided in parallelwhile having a gap from each other; a first wafer retention head and asecond wafer retention head respectively installed above the firstplaten and the second platen and being movable up and down; a wafertransfer apparatus arranged between the first platen and the secondplaten and on which the wafer before being polished and the wafer afterbeing polished are mounted; a first moving means that moves and stopsthe first wafer retention head to both positioning portions of the firstplaten and the wafer transfer apparatus; a second moving means thatmoves and stops the second wafer retention head to both positioningportions of the second platen and the wafer transfer apparatus; and athird moving means that supports the first moving means and the secondmoving means, and whirls around the wafer transfer apparatus so as tomove and stop the first wafer retention head and the second waferretention head respectively to the positioning portions of the secondplaten and the first platen, wherein the wafer polished by the firstplaten or the second platen is whirled and moved to the positioningportion of the second platen or the first platen so as to be polished.2. A wafer polishing apparatus that polishes a wafer by pressing thewafer retained by a wafer retention head to a polishing pad on a platen,comprising: a first platen and a second platen provided in parallelwhile having a gap from each other; a first wafer retention head and asecond wafer retention head respectively installed above the firstplaten and the second platen and being movable up and down; a wafertransfer apparatus arranged between the first platen and the secondplaten and on which the wafer before being polished and the wafer afterbeing polished are mounted; a first moving means that moves and stopsthe first wafer retention head to both positioning portions of the firstplaten and the wafer transfer apparatus; a second moving means thatmoves and stops the second wafer retention head to both positioningportions of the second platen and the wafer transfer apparatus; and athird moving means that supports the first moving means and the secondmoving means, and whirls around the wafer transfer apparatus so as tomove and stop the first wafer retention head and the second waferretention head respectively to the positioning portions of the secondplaten and the first platen, wherein the wafer polished by the firstplaten or the second platen is whirled and moved to the positioningportion of the second platen or the first platen so as to be polished, apartition wall for preventing a liquid from flying in all directions isprovided between the first platen and the wafer transfer apparatus, andbetween the second platen and the wafer transfer apparatus, a passagethrough which the first wafer retention head and the second waferretention head pass is formed in the partition wall, and the partitionwall is provided in such a manner as to be capable of integrallywhirling with the third moving means.
 3. The wafer polishing apparatusas claimed in claim 1 or 2, wherein the wafer transfer apparatus isprovided with a wafer carry-in means that carries in the unpolishedwafer, and a wafer carry-out means that carries out the polished wafer,and the wafer carry-out means and the wafer carry-in means arestructured such as to be independently movable to a positioncorresponding to a center position of whirling of the third movingmeans.
 4. The wafer polishing apparatus according to claim 1, 2 or 3,wherein the third moving means is provided so as to be retractable fromthe center position of whirling, and a head cleaning apparatus forcleaning the first wafer retention head and the second wafer retentionhead is installed at the center position of whirling.
 5. The waferpolishing system provided with the wafer polishing apparatus accordingto claim 1 or 2, wherein two or more the wafer polishing apparatuses areprovided in parallel, and a transfer apparatus for transferring thewafer polished by one wafer polishing apparatus to the other waferpolishing apparatus installed in adjacent thereto is provided betweenthe adjacent wafer polishing apparatuses.
 6. The wafer polishing methodof polishing a wafer by the wafer polishing system according to claim 5in which two wafer polishing apparatuses are provided in parallel,comprising: a step of transferring the wafer to one of two waferpolishing apparatuses so as to execute a one-step polishing or atwo-step polishing; a step of transferring the wafer executed theone-step polishing or the two-step polishing to the other waferpolishing apparatus by a transfer apparatus; and a step of furtherapplying the one-step polishing or the two-step polishing to the waferby the other wafer polishing apparatus, wherein a three-step polishingor a four-step polishing is applied as a whole to the wafer.